Semiconductor interconnect structure having enhanced performance and reliability

Abstract

An interconnect structure and method for fabricating the interconnect structure having enhanced performance and reliability, by minimizing oxygen intrusion into a seed layer and an electroplated copper layer of the interconnect structure, are disclosed. At least one opening in a dielectric layer is formed. A sacrificial oxidation layer disposed on the dielectric layer is formed. The sacrificial oxidation layer minimizes oxygen intrusion into the seed layer and the electroplated copper layer of the interconnect structure. A barrier metal layer disposed on the sacrificial oxidation layer is formed. A seed layer disposed on the barrier metal layer is formed. An electroplated copper layer disposed on the seed layer is formed. A planarized surface is formed, wherein a portion of the sacrificial oxidation layer, the barrier metal layer, the seed layer, and the electroplated copper layer are removed. In addition, a capping layer disposed on the planarized surface is formed.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a semiconductor integrated circuit interconnect structure and method for fabricating an interconnect structure having enhanced performance and reliability, by minimizing oxygen intrusion into a seed layer and an electroplated copper layer of the interconnect structure.[0003]2. Description of the Related Art[0004]Semiconductor devices include a plurality of circuit components (i.e., transistors, resistors, diodes, capacitors, etc.) connected together to form an integrated circuit fabricated on a semiconductor substrate. A complex network of semiconductor integrated circuit interconnects (interconnects) are routed to connect the circuit components distributed on the surface of the substrate. Efficient routing of these interconnects, across semiconductor devices, requires formation of multi-level or multi-layered patterning schemes, such as single or dual damascene interconnect structures.[...

AI Technical Summary

Benefits of technology

The invention is about a way to make an interconnect structure that works better and is more reliable. It does this by reducing oxygen from getting into the first layer and then coating it with copper. This process makes the structure perform better and last longer.

Problems solved by technology

However, when copper is utilized to form interconnects, electromigration may occur.

Electromigration can result in void formation as well as extrusion / hillock formation along regions of an interconnect structure.

The voids can result in an open circuit if one or more voids formed are large enough to sever the interconnect structure, and the extrusions / hillocks can result in a short circuit if one or more extrusions / hillocks are sufficiently long to form a region of abnormally low electrical impedance.

The oxidized barrier interface is susceptible to serving as an electromigration void nucleation site, which can result in faster growth of large electromigration voids.

Specifically, oxygen that intrudes the seed layer and electroplated copper layer may consume impurities within the interconnect structure, for example manganese and aluminum impurities, and prevent the impurities from segregating in certain regions of the interconnect structure that are susceptible to copper diffusion.

Copper diffusion can result in an increased amount of void formation and extrusion / hillock formation within the interconnect structure.

Thus, if there is insufficient segregation of impurities in certain regions of the interconnect structure that is susceptible to copper diffusion then copper diffusion may not be adequately suppressed.

Failure to adequately suppress copper diffusion within the interconnect structure can result in reduced performance and reliability of the interconnect structure due to electromigration.

As a semiconductor integrated circuit interconnect structure is generally formed using copper, which is a metal conductor susceptible to electromigration, electromigration presents a challenge when utilizing integrated circuits with a copper based interconnect structure.

The void formation and extrusion / hillock formation can reduce integrated circuit performance, decrease reliability of interconnects, cause sudden data loss, and reduce the useful life of semiconductor integrated circuit products.

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